The long-term goal of this research is to understand the mechanisms by which psychological stress triggers defects in intestinal epithelial barrier function. Previous work has demonstrated that corticotropin releasing factor (CRF), a small peptide released from the hypothalamus and intestinal tissues during the stress response, triggers the breakdown in intestinal epithelial barrier function through the activation of CRF receptors expressed on the intestinal mast cell. The proposed studies will investigate how neural signaling plays a critical role in the amplification of CRF-mast cell signaling pathways. The project, based on previous studies and recent preliminary data, will test the hypothesis, that neural-mast cell communication induces the up-regulation of mast cell signaling pathways that prime the mast cell for enhanced responsiveness to CRF. Understanding how the nervous system regulates CRF-mast cell signaling pathways is highly relevant to important GI diseases including Irritable Bowel Syndrome (IBS) and the Inflammatory Bowel Diseases (IBDs). In Specific Aim 1, RNA array technology will be utilized in nerve-mast cell co-cultures to identify the mast cell signaling pathways that are up-regulated by neural signaling. In Specific Aim 2, siRNA technology in nerve-mast cell co- cultures will be utilized to confirm the role of neural-mediated signaling pathways in mast cell responsiveness to CRF. These specific aims are designed to significantly advance our fundamental understanding of neuro- immune signaling in stress-induced GI diseases and they will likely reveal novel targets for innovative preventative and therapeutic strategies.